maxwell



Dec. 6, 1955 F. R. MAXWELL AIRPLANE WING WITH VARIABLE NOSE SLOT Re.A24,099

5 Sheets-Sheet 1 Original Filed Feb. l1, 1942 F7 Il Dec. 6, 1955 F. R.MAXWELL AIRPLANE WING wrm VARIABLE Nos sLoT 5 Sheets-Sheet 2 originalFiled reb.v 11, 1942 5 Sheds-Sheet 3 Dec. 6, 1955 F. R. MAXWELL AIRPLANEWING WITH VARIABLE NOSE SLOT Original Filed Feb. l1, 1942 Dec. 6, 1955F. R. MAXWELL AIRPLANE WING WITH VARIABLE NOSE SLOT Original Filed Feb.l1, 1942 5 Sheets-Sheet 4 amati! Y Dec. 6, 1955 F. R. MAXWELL AIRPLANWING WITH VARIABLE NOSE SLOT 5 Sheets-Sheet 5 Original Filed Feb. il,1942 www4 United States Patent Ol AIRPLANE WING WITH VARIABLE NOSE SLOTFrank R. Maxwell, Washington, D. C.

Original No. 2,381,678, dated August 7, 1945, Serial No. 430,317,February l1, 1942. Application for reissue July 27, 1955, Serial No.524,836

s Claims. (c1. 244-42) Matter enclosed in heavy brackets [l appears inthe original patent but forms no part of this reissue l cation; matterprinted in italics indicates the additions made by reissue.

. extending adjacent the leading edge from the root of the wing toadjacent the tip, in order to increase the lift on the wing and enablelower flying speeds and consequently lower landing speed.

As will be appreciated, the purpose of the wing slot is to increase theangle of incidence at which the wing stalls and thereby increase themaximum lift of the wing. However, in many wings the angle at which thevarious sections of the wing stall varies from root to tip of the wing.Thus, for example, in the case of a tapered wing the section adjacent tothe top -usually stalls before the section adjacent to the root, andvice versa in the case of a straight wing.

Desirably, in order to obtain the maximum lift, a wing slot will be sodesigned that all portions of the wing will stall at approximately thesame angle of incidence and that angle will be the largest attainable.Further, it is essential that that section of the wingvnear the tip, inthe way of the aileron, or other means of lateral control, should notstall before the center section and, preferably. a little after thecenter section, so that lateral control may be maintained at andadjacent to the point of stall of the entire wing.

As will be apparent, the slots as heretofore used and of the continuoustype are not eective to adjust the angle of incidence of a wing to themaximum obtainable amount and, atr the same time, retain adequatelateral control, when the wing is of a type such that the natural angleof stall without slots varies in different sections throughout thelateral extension of the wing.

Now in accordance with this invention, I provide a wing having means forforming a slot which is effective to adjust the angle of incidence of awing to the maximum amount with retention of lateral control up to thestall. The novel slot according to this invention comprises a pluralityof sections, adjacent the leading edge and extending from the root toadjacent the tip of the wing.

More particularly, the severalsections of the slot mayv be of differentcontour, of different length and of different n width, or tapered, al1respectively with relation to the portions of the wing and the chordthereof with which they are respectively related and the aerodynamicconditions obtaining with respect thereto. Further, the several sectionsmay be at different angles relative to the chord of the wing. Y

Further, `more particularly, means may be provided Re. 24,099 ReiaauedDec. 6, 1955 ,ICC

opened different amounts to the end that the angle of maximum lift maybe varied throughout the extension of the wing with reference to theaerodynamic effects obtaining in different portions of the wing when'theeffect of the slot is utilized.

Having now indicated in a general way the nature and purpose of thisinvention, I will proceed to a detailed description of a preferredembodiment with reference to the accompanying drawings, in which:

Figure 1 is a plan view, partly broken away, of a wing having a rearllap and provided with means for forming a slot comprising a pluralityof sections according to this invention.

Figure 2 is a sectional view on line 2-2, Figure 1, looking in thedirection of the arrows.

Figure 3 is a sectional view on line 3.3, Figure l, looking in thedirection of the arrows.

Figure 4 is a sectional view on line 44, Figure l, looking in thedirection of the arrows.

Figure 5 is a plan view, partly broken away, of a wing embodyingamodification of this invention as shown in Figure 1.

Figure 6 is a fragmentary sectional view showing means for forming oneof the slot sections in closed position with. means for opening andclosing the slot.4

Figure 7 is a sectional View showing the-subject of Figvure 6 with theslot open.

Figure 8 is a fragmental sectional view of a flap in inoperativeposition and means for its operation.

Figures 9 and 10 are diagrammatic views exemplifying the cooperativemovement of slot forming means and the flap. f

Figures 11 and 12 are fragmentary sectional views showing modificationof the means for opening and closing the slot, the slot being shownclosed in Figure 1l and open in Figure 12.

Figure 13 is a sectional fragmentary view of a rear flap with modifiedmeans for manipulating it. f

Figures 14-16 are fragmentary sectional views of other modified meansfor opening and closing the slot, the slot being shown closed in Figure14 and open in Figures 15 and 16. v

f Referring to the drawings, the fuselage of any airplane is indicatedat 1, while 2 indicates a wing. The-wing is provided adjacent itsleading edge with a slot generally indicated at 3, and formed in aplurality of sections 3A, 3Brand 3C. The several slot sections areformed by means of upper slot covers 28 and lower slot covers 30 ofany-usual construction and mounting indicated in Figures 6 and 7. Thewing is provided with a trailing edge flap 4 and an aileron 5.. v f

As shown in Figure l. the several sections forming the slot mayrespectively .vary in width with relation to the chord of the wing, itbeing noted that the several sections as shown are of uniform width, butthat, however, the chord of the wing varies in the extension of the wingfrom root to tip. However, as shown in Figure 5, a constant relationbetween slot widthand wing chord may be maintained by, as shown,tapering the slot with the taper of the wing. Again, as shown Vin Figurel, the slot sections may varyinlength, it beingV noted that the middlesection is shorter than the end sections. Y,

With reference to Figures 2-4, it will be noted that the f contour ofthe slot in cross section is varied in the several whereby the severalsections forming slot may be f' sections, the particular contour for theseveral sections As has been indicated,the slot, comprising the-sections3A, sa and sc, is adapted m be opened in cooperation with operation ofthetraiiing edge flap 4it being notedthattheseveralseetionsofthegslotmaybeopenedan 3 equal amount orrespectively in dilerent amount, and in cooperation with operation ofthe trailing edge flap.

To such end an arm 8 (Figure 8) is attached at one end to the trailingedge ilap 4, for example, to the hinge pintle 7 of the llap, which inusual manner is hinged to the wing and in inoperative position fits intoa recess 6 in the underside of the wing, and at its other end to the rod9, by a pivot 10. The rod 9 extends longitudinally of the chord of thewing and is connected to any suitable form of mechanism, as a screw andnut mechanism, indicated at 9 (Figure l) with connection to operatingmeans located conveniently to the pilot and adapted to exert a push orpull on the rod for lowering and raising the ap into and out ofoperative position. As will be apparent from an inspection of Figure l aplurality of arms and rods similar to arm'8 and rod 9 will be provided,for the operation of the ap.

A segment l1, having a plurality of openings 12 adjacent to itsperiphery, is attached, for example, to the pintle 7 or otherwise towork with arm 8. The segment ll is connected by an adjustable link 18 toa lever 13, pivotally mounted, as at 15, on a bracket 16 secured to anelement of the internal structure of the wing. One arm of the lever 13is connected to a rod 19, as at 20, while its other arm is extended andprovided with a plurality of openings 17. It will be noted from aninspection of Figure 8 that the link 18 may be connected to the segmentl1 through any one of the apertures 12 and to the lever 13 through anyone of the apertures 17.

The arm 19 extends longitudinally of the chord of the wing and ispivotally connected, as at 22 (Figures 6-7) to an arm of a bell cranklever 21, which in turn is pivotally mounted, as at 23, on an element ofthe internal structure of the wing, at a point adjacent to the slot 3.To another arm of the lever 21 is attached, as at 25, a link 24 which inturn is connected to an adjustable link or turnbuckle 26, which in itsturn is pivotally connected, as at 27, to the underside of the upperslot cover 28. The angularity of the link 24 may be adjusted withrespect to the lever 2l by means of a threaded rod 42 pivotallyconnected at one end, as at 43, to the link 24, and extending through anut 45 pivotally mounted, as at 44, on lever 21.

The third arm of the lever 2l is connected to a link 38, through a slotand pin connection 39, 40, Figures 6-7, the link 38 being in turnconnected, as at 37, to a lever 33 pivotally mounted, as at 35, on theupper slot cover 28. The lever 33 is in turn connected, as at 34, to anadjustable link 31 pivotally mounted, as at 32, on the lower slot cover30. A spring 41 is connected to the link 38 and to an element of theinternal structure of the wing.

As will be appreciated from an inspection of Figures l and 5, aplurality of rods similar to rod 19 and connections therefrom to theupper and lower slot covers 28 and 30, as through levers similar tolever 21, are provided for the covers forming the sections of the slot,as, for example, sections 3A and 3B, opposite to the rear ilap.

For operation of the covers 28 and 30 of the section 3C of the slotbeyond the outer end of the rear ap, as shown in Figure l, the outer rod19 is connected to a rod 47 extending longitudinally of the wing bymeans of a lever 48 mounted in the wing and the rod 47 is connected to apair of levers 2l through the medium of levers 46 mounted in the wingand short arms 19'.

For the operation of the covers 28 and 30 for the opening of thesections of the slot 3 in cooperation with operation of the rear ap 4,the adjustable links 18 are connected to the segments 1l and levers 13for desired relative movement of the flap and slot covers. Thus, byreference to Figure 9, it will be noted that if the links are connectedthrough the medium of the opening I in both the segment and lever, thelever 13 will not move toopentheslotuntilthesegmentltasturnedsubstantially with consequent downward movement of theap. Again (Fig. 10), if the connection between opening I in the leverand opening IV in the segment is made, the

lever willbe moved when the segment is moved with consequent opening ofthe slot when the ap starts to move downward. It follows that variousopenings of the slot as a whole or of its various sections respectivelywith respect to downward movement of the ilap may be obtained byvariously connecting the links 18 to the segments 11 and levers 13, as awhole or as they control the openings of the several slot coversrespectively.

Again, the degree of opening of the slot covers, respectively, isadjustable through adjustment of the angularity of the links 24 withrespect to the bell crank levers 21, through the medium of the threadedrods 42 and nuts 45.

The ap and slot cover operating mechanism having been adjusted for thedesired timed opening of the sec' tions of the slot with respect to theoperation of the ap and for the degree of opening of the severalsections of the slot, respectively, it is believed that the operation ofthe mechanism will be obvious, it being noted that, on operation by thepilot of the screw and nut 9' for lowering the flap 4 to an operativeposition, the segments l1 will be turned, causing the levers 13 to berocked and to push the rods 19 forward. 'l'he forward movement of therods 19 will cause the levers 21 to be rocked with the result that theupper and lower slot covers will be raised to open the slot sections 3Aand 3B. The slot section 3C will be opened at the same time through themedium of lever 48, rod 47, levers 46 and rods 19'.

It will be noted that the connections between levers 2l and the lowerslot cover and, more particularly, the slot and pin connection betweenlinks 38 and levers 21, together with the action of springs 41 on links38, will permit the lower slot covers 30 to be fully opened in theinitial opening movement of the upper slot covers 28, i. e., before theslots are efectively opened, and to permit them to remain in fully openposition during the range of movement of the upper covers 28 forelective opening of the slot sections.

As has been indicated, the several slot sections may be opened invarious timed relation to operation of the rear tlap and respectively todilerent extent by adjustment of the links 18 withrespect to thesegments 11 and levers 13 and by adjustment of the angular relationshipof the links 24 with respect to the levers 21 through the medium ofthreaded rods 42 and nuts 45.

Referring now to Figures 11 and l2, in which are shown modified meansfor opening and closing the slot, the push rod 19 is pivotally connectedto a three armed lever 5l, pivotally mounted as at 52 within the wingstructure adjacent to the slot 3, a longitudinally adjustable link 54 ispivotally connected to another arm of the lever 5l as at 53 and to theupper slot cover 55 as at 56.

The lower slot cover 59 is provided with an arm 61, to which ispivotally connected a sleeve 63, within `which is a spring 64 and withinwhich extends a rod 65 pivotally connected to the lever 51 as at 66. Therod 65 is engaged with the sleeve 63 through the medium of a slot andpin connection 67, 68. For adjustment of the slot openingin themodification of Figures ll and 12, it will be noted that the lever 5l isprovided with a plurality of apertures 70 enabling the link 54 to bevariously positioned in its connection with the lever 51. Thus, byconnecting the adjustable link 54 with the lever 51 through dierentapertures 70, the full opening of the upper slot cover can be varied, asshown in full and dot dash lines Figure l2.

Further, it will be noted from an inspection of Figure l1 that when theslot cover is closed the pivot points 52, 53 and 56 are in line andhence forces acting to open s xtheupperslotcoverarenottransmittedtootherconu'ol surfaces.

WithreferencetoFigure l3,itwillbenotedthattherearap4isoperatedthroughthemediumofanarm 7l mounted on the pintle 7 andpivotally connected to the pushrod l9at72indistinctionfrumthearrangementshown in Figure 8.

Referring now to Figures 14-16, a lever 8l is pivotally mounted withinthe wing structure as at 82. The pushrod19ispivotallyconnectedtoanarmoftheleverasat 80. An adjustable link 84is pivotally connected to the upper slot cover, as at 86, and to thelever 8l by means of `a pin 83 passed through one or another of theapertures 83'. The apertures 83', it will be noted, extend in a lineradially from the pivotal mounting 82 of the lever. The link 84 is bentto avoid interference with the pivot 82. The lower slot cover 89 isprovided with an arm 91, to which is pivotally connected, as at 109, asleeve 92 within which is a spring 93 and into which extends a rod 94pivotally connected to lever 8l, as at 95. 'lhe sleeve 92 and the rod 94are connected through the medium of slot and pin connection 96, 97.

By reference to Figure 14, in which the slot coversareshowntobeinclosedposition,itwillbenotedthat with the slot'coversclosed the pivots 83, 82, 86 are substantially in line, as are also thepivots 82, 95 and 190.

The in line relationship of the pivotal connections indicated will, aswill be appreciated, prevent the forces acting upon the upper slot coverand upon the lower slot cover from operating to open these covers, andit will also prevent transmission of auch forces to other portions ofthe mechanism.

As shown in Figure 1 6, various openings of the upper i slot cover maybe obtained by use of one or another of the openings 83' for connectionof the adjustable link 85 to the lever 81. As will be appreciated, thelower slot cover, due to the construction of the member connecting thearm 91 with the lever 8l, will be fully opened when the upper slot coveris opened, irrespective of the adjustment for amount of opening of theupper slot cover.

The several slot sections may be given the same or diferent contours andthe several sections may vary in width proportionally to the chords ofthe wing or be conetant with respect thereto.

As will be obvious from the foregoing description, the wing 2 provides amain airfoil section while the upper slot covers 28 form auxiliaryairfoil sections arranged relative to the leading edge of the mainsection 2 to form the slots 3A, 3B, 3C. The prole sections of thecovers, or auxiliary airfoil sections 28, respectively are of diterentcontour, it being noted from an inspection of Figures2,3and4thattheanglesofincidenceoftheaeveral auxiliary airfoil sectionsare ditferent, and that more apecically the angles of incidence of thesections respectivelydiminishinadirectiontromtheroottowardthe tip of themain section, i. e., the angles of incidence of the auxiliaryairfcilsections forming the slot 3B (Fig. 3) is less than that of theauxiliary airfoil section forming the slot 3A (Fig. 2) and that of theauxiliary airfoil seo tion forming the slot 3C (Fig. 4) is less thanthat of the auxiliary airfoil section forming the slot 3B (Fig. 3). Aswill also be obvious, if a single auxiliary airfoil section, inplace ofa plurality of auxiliary airfoil sections,isprovidedtoformasingleslogprotlesectionsofthe auxiliary airfoil sectiontaken at diterent points in its longitudinal extension will be ofdiferent contour.

It will now be appreciated that by virtue of this invention a slotextending eectvely from the root of a wing to adjacent its tip, isprovided which aerodyuamically will exactly complement the variousaerodynamic conditionsobtaininginthevariouspartsofthewinginitslongitudinalextensionsothatmaximumlifteectwillbeobtained from the slot without negative eect upon lateral stability.

Itwillbeappreciatedthatitisnotintendedthatthis 6 invention shall belimited to the details of construction described herein, it beingobvious that various structural modifications may be made withoutdeparting froml the scope of the claims appended hereto.

What I claim and desire to protect by Letters Patent is:

l. [An airfoil] An airplane wing having a root and a tip and comprisinga main airfoil section and an auxiliary airfoil arranged relative to theleading edge ofthe main section to form a slot, said auxiliary airfoilbeing characterized by the fact that the angle of incidence of theprofile sections thereof taken at a plurality of dierent points in itslongitudinal extension diminishes progressively in a direction from theroot toward the tip of the main airfoil section.

2. [An airfoil] An airplane wing having a root and a tip and comprisinga main airfoil section and an auxiliary airfoil movable relative to theleading edge of the main section and adapted to be positioned to form aslot, said auxiliary airfoil being characterized by the fact that prollesections thereof taken at a plurality of dilierent points in itslongitudinal extension are of Adierent contour, the ratio of the widthof the said auxiliary airfoil to the' chord of the wing increasingprogressively from the root toward l the tip.

3. [An airfoil] An airplane wing having a root and a from the roottoward the tip.

4. [An airfoil] An airplane wing having a root and a tip and comprisinga main airfoil section and an auxiliary airfoil movable relative to theleading edge of the main section and adapted to be positioned to form aslot, said auxiliary airfoil being characterized by the fact that theangles of incidence of proile sections thereof taken at a plurality ofdierent points in its longitudinal extension diminish progressively in adirection from the root toward the tip of the main airfoil section.

5. [An airfoil] An airplane wing having a root and a tip and comprisinga main airfoil section and a plurality of auxiliary airfoils movablerelative to the leading edge of the main section and adapted to bepositioned to form a plurality of slots extending successively in adirection from the root to the tip of the main airfoil section, saidauxiliary airfoil sections being characterized by the fact that theirprotle sections respectively are of dierent contour, the ratio of thewidth of the said auxiliary air foils to the chord of the wingincreasing progressively from the root toward the tip.

6. [An airfoil] An airplane wing having a root and a tip and comprisinga main airfoil section and a plurality of auxiliary airfoils movablerelative to the leading edge of the main section and adapted 'to bepositioned to form a plurality of slots extending successively in adirection from the root to the tip of the `main airfoil section, saidauxiliary airfoil sections being characterized by the fact that theirprofile sections respectively are of dierent length, the ratio of thewidth of the said auxiliary airfoil: to the chord of the wing increasingprogressively from the root toward the tip.

7. [An airfoil] An airplane wing having a root and a tip and comprisinga main airfoil section and a plurality of auxiliary airfoils movablerelative to the leading edge of the main section and adapted to bepositioned to form slots, said auxiliary airfoils being characterized bythe4 fact that prolle sections thereof taken at a plurality of dierentpoints in the longitudinal extensions thereof are of dilierent contour,the angles of incidence of said aux illary airfoils diminishing from theroot toward the tip,

andlfurther characterized by the fact that means are pro- RdereleelCited in the le of this patent vided for moving the nuriliary airfolsrespectively to n or the original patent different extent relative t0the leading edge 0f the mnin I l UNITED STATES PATENTS airfoil section.f

s, [An airfoil] An airplane wing having n root und a 5 1'472199 Thomsonoct' 30 1923 rip and comprising a main airfol section and a plurality1'862'902 McDonnell June 14 1932 0f auxiliary airfoils movablerelativeto the leading edge "880367 Maxwell Oct 4' 1932 of the mainsection and adapted to be positioned to form 2'041'688 Bamba May 26'1936 a plurality of slots extending successively in a diremo!! 2070'705Bamba Fb' 16' 1937 from me root o me tip of the main aixfcil section and10 f ,)eisl' 32 means for moving the auxiliary axrforls respectivelyrela 2.298,2 cm1 et al. oct. 13 1942 ent angles of incidence relative tothe main airfoil section, 2'324303 Johnson July 13' 1943 the saidlangles of incidence diminishing progressively 15 FOREIGN PATENTS f'o'"he '0' award he "P- 311,442 Great Britain Apr. 2s. 1932 517,422 GreatBritain Ian. 30, 1940

